The depth from front or outpost zone to reserve or battle zone was about 2,000 yards.

With only three battalions in a brigade, there was no option but to assign one battalion in each brigade to the defence of the outpost zones, and keep two battalions in depth in the battle zone.

With battalions at just over half-strength, and with the undulating nature of the ground, the defence resolved itself everywhere into a succession of posts with a very limited field of fire.
A good corps line called the Vaux-Morchies Line had been dug, the nearest portion a mile behind the reserve line, and this was held by the Pioneers and R.E., owing to scarcity of numbers.
The Right Group, R.F.A.

(Lt.-Col.

H.Weber), consisting of 2nd Brigade (less 21st Battery), supported the 18th Infantry Brigade; the Left Group (Lt.-Col.